mpeg1or2demuxedelementarystream.cpp

流媒体传输协议的实现代码,非常有用.可以支持rtsp mms等流媒体传输协议

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// "liveMedia"
// Copyright (c) 1996-2004 Live Networks, Inc.  All rights reserved.
// A MPEG 1 or 2 Elementary Stream, demultiplexed from a Program Stream
// Implementation

#include "MPEG1or2DemuxedElementaryStream.hh"

////////// MPEG1or2DemuxedElementaryStream //////////

MPEG1or2DemuxedElementaryStream::
MPEG1or2DemuxedElementaryStream(UsageEnvironment& env, u_int8_t streamIdTag,
			    MPEG1or2Demux& sourceDemux)
  : FramedSource(env),
    fOurStreamIdTag(streamIdTag), fOurSourceDemux(sourceDemux), fMPEGversion(0) {
  // Set our MIME type string for known media types:
  if ((streamIdTag&0xE0) == 0xC0) {
    fMIMEtype = "audio/MPEG";
  } else if ((streamIdTag&0xF0) == 0xE0) {
    fMIMEtype = "video/MPEG";
  } else {
    fMIMEtype = MediaSource::MIMEtype();
  }
}

MPEG1or2DemuxedElementaryStream::~MPEG1or2DemuxedElementaryStream() {
  fOurSourceDemux.noteElementaryStreamDeletion(this);
}

void MPEG1or2DemuxedElementaryStream::doGetNextFrame() {
  fOurSourceDemux.getNextFrame(fOurStreamIdTag, fTo, fMaxSize,
			       afterGettingFrame, this,
			       handleClosure, this);
}

void MPEG1or2DemuxedElementaryStream::doStopGettingFrames() {
  fOurSourceDemux.stopGettingFrames(fOurStreamIdTag);
}

char const* MPEG1or2DemuxedElementaryStream::MIMEtype() const {
  return fMIMEtype;
}

unsigned MPEG1or2DemuxedElementaryStream::maxFrameSize() const {
  return 65536;
      // because the MPEG spec allows for PES packets as large as ~65536 bytes
}

void MPEG1or2DemuxedElementaryStream
::afterGettingFrame(void* clientData,
		    unsigned frameSize, unsigned numTruncatedBytes,
		    struct timeval presentationTime,
		    unsigned durationInMicroseconds) {
  MPEG1or2DemuxedElementaryStream* stream
    = (MPEG1or2DemuxedElementaryStream*)clientData;
  stream->afterGettingFrame1(frameSize, numTruncatedBytes,
			     presentationTime, durationInMicroseconds);
}

void MPEG1or2DemuxedElementaryStream
::afterGettingFrame1(unsigned frameSize, unsigned numTruncatedBytes,
		     struct timeval presentationTime,
		     unsigned durationInMicroseconds) {
  fFrameSize = frameSize;
  fNumTruncatedBytes = numTruncatedBytes;
  fPresentationTime = presentationTime;
  fDurationInMicroseconds = durationInMicroseconds;

  fLastSeenSCR = fOurSourceDemux.lastSeenSCR();
  fMPEGversion = fOurSourceDemux.mpegVersion();

  FramedSource::afterGetting(this);
}